NGC 6751, also known as the Glowing Eye Nebula, is a

planetary nebula A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelated to planets. The ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Aquila Aquila may refer to: Arts, entertainment, and media * ''Aquila'', a series of books by S.P. Somtow * ''Aquila'', a 1997 book by Andrew Norriss * ''Aquila'' (children's magazine), a UK-based children's magazine * ''Aquila'' (journal), an orni ...

. It is estimated to be about 6,500

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s (2.0 kilo

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (AU), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...

s) away. NGC 6751 was discovered by the astronomer

Albert Marth Albert Marth (5 May 1828 – 6 August 1897) was a German astronomer who worked in United Kingdom, Britain and Ireland. Life After studying theology at the University of Berlin, his interest in astronomy and mathematics led him to study astro ...

on 20 July 1863.

John Louis Emil Dreyer John Louis Emil Dreyer (13 February 1852 – 14 September 1926), also Johan Ludvig Emil Dreyer, was a Danish astronomer who spent most of his career working in Ireland. He spent the last decade of his life in Oxford, England. Life Dreyer ...

, the compiler of the

New General Catalogue The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxy, galaxies, star cluste ...

, described the object as "pretty bright, small". The object was assigned a duplicate designation, NGC 6748. The nebula was the subject of the winning picture in the 2009 Gemini School Astronomy Contest, in which Australian high school students competed to select an astronomical target to be imaged by

Gemini Gemini most often refers to: * Gemini (constellation), one of the constellations of the zodiac * Gemini (astrology), an astrological sign Gemini may also refer to: Science and technology Space * Gemini in Chinese astronomy, the Gemini constellat ...

. NGC 6751 is an easy telescopic target for

deep-sky A deep-sky object (DSO) is any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed fa ...

observers because its location is immediately southeast of the extremely red-colored cool

carbon star A carbon star (C-type star) is typically an asymptotic giant branch star, a luminous red giant, whose Stellar atmosphere, atmosphere contains more carbon than oxygen. The two elements combine in the upper layers of the star, forming carbon monox ...

V Aquilae V Aquilae (V Aql) is a carbon star and semiregular variable star in the constellation Aquila. It has an apparent magnitude which varies between 6.6 and 8.4 and is located around away. V Aquilae is a type of star with a spectrum that i ...

Properties

NGC 6751, like all

e was formed when a dying

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

threw off its outer layers of gas several thousand years ago. It is estimated to be around 0.8 light-years in diameter. NGC 6751 has a complex

bipolar Bipolar may refer to: Astronomy * Bipolar nebula, a distinctive nebular formation * Bipolar outflow, two continuous flows of gas from the poles of a star Mathematics * Bipolar coordinates, a two-dimensional orthogonal coordinate system * Bipolar ...

structure. There is a bright, inner bubble (shown in the photo), as well as two fainter halos. (The outer halo, with a radius of 50 is extremely faint and is broken, while the inner halo with a radius of 27 is roughly spherical). On both the west and east sides of the inner shell, knots can be seen that are surrounded by faint "lobes". These lobes are actually a ring, and the eastern side is nearer than the western side. As a whole, the system is approaching the Solar System with a heliocentric

radial velocity The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity ...

of −31.7 km/s. The central star of the nebula has a similar spectrum to a

Wolf–Rayet star Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectroscopy, spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very ...

(spectral type C4, and has an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of about 140,000 K and a radius of about . It is losing mass at a rate of per year, and its surface composition is mostly

helium Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is ...

and

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

. The winning image of the 2009 Gemini Astronomy Contest shows a nebula at the top left of NGC 6751. This 80 x 40 arcsec nebula was discovered in 1990 by Hua & Louise at the Newton focus of the Foucault telescope, 120cm in diameter at

Observatoire de Haute Provence The Haute-Provence Observatory (OHP, ) is an astronomical observatory in the southeast of France, about 90 km east of Avignon and 100 km north of Marseille. It was established in 1937 as a national facility for French astronomers. Astro ...

(O.H.P.) Saint Michel l'Observatoire.

References

External links

* *
NGC 6751
seds.org * {{DEFAULTSORT:NGC 6751 Planetary nebulae 6751 Aquila (constellation) 177656

Properties

See also

References

External links